82-remove-duplicates-from-sorted-list-ii.md

82. Remove Duplicates from Sorted List II - 删除排序链表中的重复元素 II

给定一个排序链表，删除所有含有重复数字的节点，只保留原始链表中 没有重复出现 的数字。

示例 1:

输入: 1->2->3->3->4->4->5
输出: 1->2->5

示例 2:

输入: 1->1->1->2->3
输出: 2->3

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题目标签：Linked List

题目链接：LeetCode / LeetCode中国

题解

Language	Runtime	Memory
cpp	4 ms	1.3 MB

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
static auto _ = [](){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    return 0;
}();

class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        if (!head || !head->next) { return head; }
        ListNode* g = new ListNode(0);
        g->next = head;
        ListNode* p = g;
        ListNode* q = head->next;
        while (q) {
            if (q->val == p->next->val) {
                q = q->next;
            } else {
                if (p->next->next != q) {
                    p->next = q;
                } else {
                    p = p->next;
                }
                q = q->next;
            }
        }
        if (p->next->next != q) {
            p->next = q;
        }
        return g->next;
    }
};